1. Field of the Invention
This invention relates broadly to a temperature measuring system having means to detect and indicate both good and abnormal temperature traces and issue only the last good trace to an industrial process controller.
2. Description of the Prior Art
Many industrial processes require an accurate and continuously reliable temperature measurement of the starting material so that a satisfactory finished product may be manufactured. In the process of continuously casting steel slabs, for example, molten metal from a tundish is continuously introduced into a water-cooled mold where initial solidification takes place in the form of a frozen metal skin surrounding a liquid core as the cast product continuously leaves the mold. It is extremely important to have available at all times the tundish temperature, that is, the starting material temperature, in order that the proper caster speed and mold heat removal control may be effected to prevent a breakout in the skin below the mold.
Heretofore, tundish temperature measuring equipment consisted essentially of tundish temperature probe means and a temperature recorder having a retransmitting slidewire to provide a tundish temperature signal for use in a caster speed and mold heat removal controller. The probe means includes a detachably mounted inexpensive pole with a temperature sensor, such as a thermocouple, at its tip. The pole is insertable by an operator into the tundish molten metal during caster operation. Because of the tundish hostile environment at a temperatures ranging from 1204.degree.-1760.degree. C. (2200.degree.-3200.degree. F.), good electrical connections at the pole point of detachment are not always made or visible. Also, the sensor is subjected to both thermal and mechanical stresses which fatigue the sensor and cause a thermocouple to burn out. Consequently, at times the probe means temperature trace is subject to error and/or discontinuities and these abnormalities have a profound effect on casting machine control. Temperature trace abnormalities may cause unnecessary casting machine slowdown, or even shutdown, the latter having serious economic and safety consequences.